A knitted mesh of polypropylene monofilament has been used for many years as a prosthesis for the repair of hernias and to close defects in the abdominal and chest walls.
The knitted mesh has been resistant to infection because of the open, porous construction of the weave and because it is made from monofilament rather than a braided yarn. Tissue grows to some extent through the mesh quite rapidly and it serves as an excellent reinforcement for the tissues.
The knitted mesh is frequently used in strips measuring one inch, two inches and ten inches in width. A selvedge edge, usually braided dacron, is provided on both edges of the strips to prevent unraveling or fraying of the mesh at the edges. This is very important because in hernia repair, sutures are placed through the mesh at the two borders to secure it to the tissues and frequently considerable tension is exerted on the border of the mesh. Selvedge edges cannot be placed on the two ends of the mesh strip because it has to be cut to size (crosswise) according to the size of the defect.
If the wound becomes infected, the selvedge edge retains infection because of the multiple filament yarn construction of the selvedge edge. This results in prolongation of the wound infection and frequently infected draining sinus tracts originating from the selvedge edge develope. This requires further surgery to remove the infected selvedge edge.
Examples of such knitted surgical mesh and methods of repairing body tissues with such surgical mesh are disclosed in my prior U.S. Pat. Nos. 3,054,406 and 3,124,136. In addition, Davol, Inc. has been marketing monofilament polypropylene mesh with selvedge edges under the Trademark "Davol/Usher's Marlex Mesh" as described above for many years.
It would be highly desirable to provide a knitted surgical mesh of greater porosity allowing better growth of tissue through it, one which is free of selvedge edges thereby avoiding retention of contamination or infection, and a mesh of greater strength and flexibility than prior surgical meshes. It is not possible to increase the porosity of prior flat surgical meshes because to provide a mesh of more open weave, the diameter of the threads would have to be increased which would make the mesh too stiff for practical use. Polypropylene mesh having a monofilament diameter of 6 mils and 68 stitches or courses to the inch is presently in use, and to make an open weave would require too large a monofilament diameter and thus provide too stiff a mesh.